Passive Safety Lines for Floating Wind Power Cable Protection
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Solution Overview
Problem
Non-redundant mooring systems in floating offshore wind turbines lead to significant over-stressing and failure of power cables upon failure of a main mooring line, resulting in high repair costs and downtime, with existing solutions requiring active tensioning means or being load-bearing components.
Innovation Solution
Implementing passive safety lines oriented parallel to power cables, with lengths and strengths designed to prevent over-stressing by taking over mooring loads when a main mooring element fails, maintaining the position of the floating wind turbine and protecting the power cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-redundant mooring system with few mooring lines is used to reduce development cost, then the cost of development is reduced, but upon failure of a mooring line the floating wind turbine experiences significant position change causing over-stressing and failure of power cables
Solution Approach 1:
The mooring system is segmented into two distinct functional parts: main mooring lines for primary station-keeping and load-bearing, and passive safety lines for cable protection. This segmentation allows each component to be optimized for its specific function, with safety lines having lower breaking strength designed solely to protect power cables without interfering with normal mooring operations
Solution Approach 2:
Passive safety lines act as intermediary elements between the main mooring system and the power cables. When a main mooring line fails, these safety lines engage as a mediating mechanism to limit the displacement of the floating wind turbine, thereby preventing direct transmission of excessive forces to the power cables
2Reliability
If passive safety lines with breaking strength lower than main mooring lines are used to protect power cables, then power cable protection is achieved, but the safety lines must be carefully designed to not interfere with normal mooring operations
Solution Approach 1:
The breaking strength parameter of the passive safety lines is deliberately set lower than that of the main mooring lines. This parameter change ensures that safety lines engage only when needed (after main line failure) while remaining slack during normal operations, thus providing protection without adding operational complexity
3Reliability
If the safety line length is shorter than the power cable length to prevent over-stressing, then power cable capacity limits are maintained, but the safety line must be precisely sized to remain unstressed during normal maximum displacement
Solution Approach 1:
The passive safety lines are designed with a length that is partially sufficient for normal operations (remaining unstressed during maximum displacement) but becomes excessive (tightens) when needed for protection (after mooring line failure). This partial/excessive approach simplifies design by using a single length specification that automatically provides both normal operation freedom and emergency protection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents power cable damage and maintains station-keeping ability, reducing repair costs and downtime by using passive safety lines that absorb mooring loads, ensuring the power cables operate within their capacity limits.
Implementation Method 1
the safety line has marginal influence to the behavior of the floating wind turbines when all the main mooring lines are intact
Implementation Method 2
the at least one seabed power cable safety line takes the mooring loads instead of the power cable
Data Source
AI summary
A system for preventing damage to a power cable for electric power transmission to and from and within a floating offshore wind power plant using non-redundant mooring, after failure of a main loadbearing mooring element is described, comprising at least one power cable safety line having the following properties: It is connected to the same two wind turbines as the power cable it is designed to protect. It has an effective length shorter than the power cable it is designed to protect. It has an effective length longer than what is needed to remain largely unstressed when the distance between the floating wind turbines with intact mooring systems is at its maximum. It has a breaking strength being a predetermined fraction of the strength, which the main loadbearing mooring elements are designed for.